Closed cycle refrigeration system



March 1965 A. SILVER 3,171, 68

CLOSED CYCLE REFRIGERATION SYSTEM Filed May 1, 1962 2 Sheets-Sheet 1 INTEE-C001. ER

E VA PORA TOR REFRIGERATED SPACE INVENTOR. ALEXANDER SILVER,

BY vzwfipi A Home March 2, 1965 A. SILVER 3,171,258

CLOSED CYCLE REFRIGERATION SYSTEM Filed May 1, 1962 Fig.2

2 Sheets-Sheet 2 E VAPOR/170R RE FR/GERA TED SPACE IN TEE-6 OOLERINVENTOR.

ALEXANDER SILVER,

United States Patent ice 3,171,268 CLOSED CYCLE REFRIGERATION SYSTEMAlexander Silver, Tarzana, Calif, assignor to The Garrett Corporation,Los Angeles, Calif, a corporation of California Filed May 1, 1962, Ser.No. 191,543 3 Claims. (Cl. 62-498) This invention relates to a closedcycle refrigeration system and in particular relates to a closed vaporcycle refrigeration system in which an expansion turbine is utilized inconjunction with an external power source to operate a centrifugalcompressor which impels refrigerant fluid through the refrigerationsystem.

In the operation of a closed cycle refrigeration system it is oftendesired to utilize a centrifugal compressor assembly capable ofpropelling a large volume of refrigerant fluid at a low pressure. Insuch systems difficulty sometimes is encountered in obtainingsufficiently high discharge pressure from the compressor so thatrefrigerant vapor may be condensed when the coolant fluid, utilized foreffecting vapor condensation, has a relatively high temperature. Whenthe temperature of the coolant is high and the pressure of therefrigerant fluid is correspondingly low condensation of refrigerantvapor will not be effected. Under these conditions an expansion valveand an evapo-- rator unit, which constitute a part of such a refrigerantcycle, are not capable of performing their designed function.

When the closed cycle refrigeration system is operating effectivelyrefrigerant liquid is delivered to an expansion valve and an evaporatorunit. The refrigerant liquid absorbs heat from the space to berefrigerated and the refrigerant liquid thereby is transformed from aliquid to a vapor state. Thus, it is apparent that when refrigerantvapor is not condensed to a liquid state prior to its delivery to anexpansion valve and evaporator unit these portions of the refrigerantcycle cannot function properly and the desired refrigeration effectcannot be achieved.

Further, in the operation of a closed cycle refrigeration systemconsiderable power is required for operating the equipment used topropel refrigerant fluid through the system. For example, in order tocreate a desired volume flow rate and fluid pressure condition for therefrigerant fluid, excessively large and complex motive equipment may berequired. This motive equipment demands a high energy supply source sothat the desired conditions of flow rate and pressure may be maintainedwithin the refrigeration system. In providing for economical andeffective refrigeration the conservation of power is an important resultto be achieved.

Accordingly, it is an object of this invention to provide a closed cyclerefrigeration system wherein a high volume flow rate of refrigerantfluid is maintained with the use of a minimum amount of power from anoutside source.

Another object of this invention is to provide a refrigeration systemwhich is versatile as to the type of refrigerant fluids which may beutilized in achieving economical and effective refrigeration.

Another object of this invention is to provide a closed cyclerefrigeration system in which predetermined pressure and temperatureconditions are easily maintained for the effective condensation ofrefrigerant vapor.

Another object of this invention is to provide a refrigerant system inwhich refrigerant fluid is transferred at low pressure to an intercoolerunit in which the temperature of coolant fluid may be maintained at arelatively high level.

That these and other objects and advantages of the invention areobtained will be readily apparent from the following detaileddescriptions, when read in conjunction with the accompanying drawings inwhich:

FIGURE 1 is a schematic diagram showing the closed cycle refrigerationsystem;

FIGURE 2 is a schematic diagram showing the same system with a liquidpump included in the system.

Referring to FIGURE 1 of the drawings, reference character 1 designatesan expansion valve. A portion of the refrigerant liquid which flowsthrough valve 1 is expanded into a vapor state. The refrigerant fluidwhich flows from expansion valve 1 passes into an evaporator unit 2.Evaporator 2 is located within the space 3 which is to be cooled byrefrigeration. Refrigerant fluid flowing through evaporator 2 absorbsheat from the space 3. As heat is absorbed by the refrigerant fluid thefluid is transformed into a vapor state. Refrigerant vapor then flowsfrom evaporator 2 into a compressor unit 4. In this refrigeration cyclecompressor 4 may be a centrifugal compressor which iscapable ofproducing a large volume flow rate at a low discharge pressure.

Refrigerant vapor is discharged from compressor 4 into an intercoolerunit 5. A coolant fluid 6 is circulated through the intercooler 5 by anywell known means for producing fluid circulation. Heat in therefrigerant vapor is transferred to the coolant fluid 6 before therefrigerant vapor flows into a condenser-evaporator unit 7, or through aturbine 8. Reference character 9 designates a valve which controls theflow of coolant fluid to the intercooler unit 5.

Referigerant vapor flowing from intercooler 5 into turbine 8 passesthrough a valve 10. Valve 10 may be operated to control the flow ofrefrigerant vapor to turbine 8. The flow of refrigerant vapor throughturbine 8 imparts a propelling force to the blading structure within theturbine unit. Also, in flowing through turbine 8 the refrigerant vaporundergoes an isentropic expansion.

Turbine 8 is connected by .a shaft 11 to compressor 4. The rotation ofturbine 8 drives compressor 4 through the shaft connection 11. A motor12 also is connected to compressor 4 through shaft 11. Turbine 8 andmotor 12 share the load in driving compressor 4.

As refrigerant vapor undergoes isentropic expansion through turbine 8the temperature of the refrigerant vapor is lowered. Refrigerant vaporfrom turbine 8 flows through coils 13 within condenser unit 7. The lowtemperature vapor flowing from turbine 8 through coils 13 absorbs heatfrom refrigerant fluid flowing from intercooler 5. Thus, a furtherlowering of the temperature of the refrigerant fluid from intercooler 5is effected by the heat exchange process which takes place withincondenser 7. When none of the refrigerant fluid flowing from intercooler5 has been changed to a liquid state prior to its entry into condenser 7the heat exchange process within condenser 7 effects completecondensation of this fluid. In the event that fluid is completelycondensed in intercooler 5, valve 10 may be closed and turbine 8 may betaken out of the closed vapor system. In this latter event the solefunction of condenser unit 7 is to collect condensate from intercooler5.

The operational position of valve 10 controls the amount of fluid whichis passed through turbine 8. Thus, valve 10 may be used to control theamount of power supplied to compressor 4 by the turbine 8.

It is apparent that while turbine 8 is operating the power required tooperate motor 12 for driving compressor 4 will be substantially reduced.Also, it is apparent that in this refrigeration system there is nonecessity for maintaining a substantially low temperature for thecoolant fluid which flows through an intercooler in order to obtaineffective cooling within the space cooled by refrigeration.

Patented Mar. 2, 1965,

FIGURE 2 shows the same refrigeration system as illustrated in FIGURE 1with the exception that a liquid boost pump has been added to thesystem. The addition of. this pump is for the purpose of mtainingadequate circulation pressure. within the system when the evaporatorunit and the space to be refrigerated are located at a substantiallyhigher elevation than other equipment used in the system. The liquidpump 14 is driven by motor 12 through gear connections 15 and 16. Thus,by the addition of pump 14 eflicient refrigeration is assured regardlessof the elevated location of the space that requires refrigeration.

It will be apparent to those skilled in the art that the novelprinciples of the invention disclosed herein will suggest various othermodifications and applications of the same. It is accordingly desiredthat the present invention shall not be limited to the specificembodiment thereof described herein.

Having thus described my invention I claim:

1. A closed cycle refrigeration system comprising:

a centrifugal compressor for producing a high volume flow rate ofrefrigerant fluid at a low discharge pressure;

heat exchange means for cooling fluid discharged by said compressor;

a turbine driven by expansion of a portion of the fluid cooled by saidcooling means, said turbine being connected to said compressor to drivesaid compressor;

additional drive means coupled with said compressor to assist in drivingthe same;

a condenser unit including conduit means coupled with said heat exchangemeans for condensing the remainder of vapor flowing from said coolingmeans;

conduit means within said condenser unit through which fluid exhaustedfrom said turbine is circulated in heatexchanging relation to saidremainder of the vapor to condense same;

an expansion valve in fluid communication with said condenser;

an evaporator unit connected to said expansion valve to receivevaporized fluid therefrom, said evaporator unit being located in a spacewhich is to be cooled by refrigeration; and

conduit means delivering vaporized fluid directly from the evaporatorunit and from the condenser to said compressor.

2. A closed cycle refrigerant system in accordance with claim 1 in whichsaid turbine is an isentropic expansion device and said refrigerantfluid flowing through said turbine undergoes an isentropic expansion.

3. A closed cycle refrigeration system comprising:

a rotary centrifugal compressor for producing a high 7 volume flow rateof refrigerant fluid at a low discharge pressure;

heat exchange means for cooling fluid discharged by said compressor;

a turbine driven by expansion of a first portion of the fluid cooled bysaid cooling means, said turbine being mechanically connected to saidcompressor to drive said compressor;

electric motor means operated by an outside source of electric power fordriving said compressor, said motor means and said turbine sharing theload of driving said compressor;

a condenser unit including conduit means coupled with said heat exchangemeans for condensing a second portion of the vapor flowing from saidcooling means;

conduit means within said condenser unit through which fluid exhaustedfrom said turbine is circulated in heat-exchanging relation to saidsecond portion of the vapor to condense same;

an expansion valve in fluid communication with said condenser;

an evaporator unit connected to said expansion valve to receivevaporized fluid therefrom, said evaporator unit being located in a spacewhich is to be cooled by refrigeration;

and conduit means delivering vaporized fluid directly from theevaporator unit and from the condenser to said compressor withoutsubstantial addition of heat to the vaporized fluid.

References Cited in the file of this patent UNITED STATES PATENTS1,379,102 Jefleries May 24, 1921

1. A CLOSED CYCLE REFRIGERATION SYSTEM COMPRISING: A CENTRIFUGALCOMPRESSOR FOR PRODUCING A HIGH VOLUME FLOW RATE OF REFRIGERANT FLUID ATA LOW DISCHARGE PRESSURE; HEAT EXCHANGE MEANS FOR COOLING FLUIDDISCHARGED BY SAID COMPRESSOR; A TURBINE DRIVEN BY EXPANSION OF APORTION OF THE FLUID COOLED BY SAID COOLING MEANS, SAID TURBINE BEINGCONNECTED TO SAID COMPRESSOR TO DRIVEN SAID COMPRESSOR; ADDITIONAL DRIVEMEANS COUPLED WITH SAID COMPRESSOR TO ASSIST IN DRIVING THE SAME; ACONDENSER UNIT INCLUDING CONDUIT MEANS COUPLED WITH SAID HEAT EXCHANGEMEANS FOR CONDENSING THE REMAINDER OF VAPOR FLOWING FROM SAID COOLINGMEANS; CONDUIT MEANS WITHIN SAID CONDENSER UNIT THROUGH WHICH FLUIDEXHAUSTED FROM SAID TURBINE IS CIRCULATED IN HEATEXCHANGING RELATION TOSAID REMAINDER OF THE VAPOR TO CONDENSE SAME; AN EXPANSION VALVE INFLUID COMMUNICATION WITH SAID CONDENSER; AN EVAPORATOR UNIT CONNECTED TOSAID EXPANSION VALVE TO RECEIVE VAPORIZED FLUID THEREFROM, SAIDEVAPORATOR UNIT BEING LOCATED IN A SPACE WHICH IS TO BE COOLED BYREFRIGERATION; AND CONDUIT MEANS DELIVERING VAPORIZED FLUID DIRECTLYFROM THE EVAPORATOR UNIT AND FROM THE CONDENSER TO SAID COMPRESSOR.